1. Field of the Invention
The present invention relates to shampoos containing polymeric hair conditioning agents.
2. The Prior Art
Conventional hair conditioning shampoos generally comprise one or more anionic surfactants such as sodium or ammonium lauryl sulfate or laureth sulfate to wash off oil and dirt from the hair and one or more hair conditioning agents to enhance combability and lustre, detangle the hair, reduce static electricity, etc. Among the hair conditioning agents traditionally incorporated in hair conditioning shampoos are water-insoluble silicones (e.g., dimethicone) and cationic polymers with quaternary moieties.
The latter readily adhere to hair because of the inherent anionic change in individual hair fibers. However, the cationic nature of the polymers also contribute to instability of the shampoo formulation because of the anionic nature of the surfactant. The mutual attraction between the anionic surfactant and the cationic polymer results in reduced deposition of the polymer in the hair, cloudiness in the shampoo product and a reduction in the foamability of the shampoo.
It would be desirable to increase the charge density of the cationic polymers to further enhance the attraction thereof and adherence to the anionic keratin hair fibers. However, increasing the charge density also exacerbates the disadvantages noted above connected with the use of cationic polymers in formulations containing anionic agents.
It has been common practice to employ water-insoluble silicones in conjunction with cationic polymers as co-hair conditioners to alleviate some of the disadvantages associated with the latter since they carry no charge and do not interact with anionic surfactants. The addition of silicones, however, adds to the complexity of the final mixture, rendering it less stable as well as increasing the cost of the final shampoo product.
Moreover, the anionic surfactants conventionally employed in hair conditioning shampoos, i.e., the salts of lauryl sulfate and laureth sulfate, are somewhat harsh to hair fibers in that they tend to dissolve some of the hair protein.
It is an object of the present invention to provide a stable hair conditioning shampoo comprising an anionic surfactant and a high charge density cationic polymer hair conditioner which enables the elimination of or at least a reduction in the amount of water-insoluble silicone hair conditioning agent, which is highly adherent to hair fibers and which is less harsh to hair protein than conventional hair conditioning shampoos.